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7/29 Astronomy with Neutral Atoms – IBEX Catches the Interstellar Wind and Images the Heliospheric Boundary

Published on July 22, 2013

Speaker:Eberhard Möbius (University of New Hampshire)

Seminar Abstract:

400 years after Galileo pointed a telescope at celestial objects for the first time, neutral atoms were added to the astronomical toolbox with the Interstellar Boundary Explorer (IBEX), launched October 19, 2008. Since early 2009, two energetic neutral atom (ENA) cameras take global images of the solar system’s interaction with its neighborhood. They have returned stunning images of the heliospheric boundary region, where the solar wind slows down in response to the surrounding interstellar medium, including the front and tail region of the heliosphere. Most unexpectedly, the images show a bright and persistent “Ribbon” across the sky, which provides a marker for the direction of the interstellar magnetic field, but the processes leading to the bright ENA emission are still being investigated. Time variations in the structures that emerged already after the first 6 months provide additional constraints. The IBEX-Lo camera also catches the interstellar wind of neutral H, He, O, and Ne atoms that blows through the solar system with a speed of ≈23 km/s and arises from the motion of the Sun relative to the neighboring interstellar gas cloud. This interstellar gas flow provides an excellent probe of the state of the local interstellar cloud (LIC) and its interaction with the heliospheric boundary region. We are likely still in the LIC for which astronomical observations place the solar system at the trailing edge and about to exit.